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Thread: Jetting too lean for psi pipes?

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    Default Jetting too lean for psi pipes?

    I just purchased a 95 v4 800 and it had a blown cylinder. Rest of sled was well cared for with 3k. Sled has psi pipes and supposedly stock everything else. Main jets are only 145 in all 4 carbs. Pilot jets are stock at 147.5. Should i consider going up a bit on both main and pilot?

  2. #2
    Site Admin/CEO MrSled's Avatar
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    Quote Originally Posted by j2hizzo View Post
    I just purchased a 95 v4 800 and it had a blown cylinder. Rest of sled was well cared for with 3k. Sled has psi pipes and supposedly stock everything else. Main jets are only 145 in all 4 carbs. Pilot jets are stock at 147.5. Should i consider going up a bit on both main and pilot?
    You could go up but are you sure it was burn down on jetting and not dirty carbs?
    Castle X Gear and more...

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    VIP Member A couple of bucks's Avatar
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    Going bigger w/ PSIs is not normal.
    Dannyboy

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    Hard telling. Im sure carbs werent clean.im just not familiar with this pipe setup. I know the typical rule of thumb is go up in jets when putting extra pipes on a 2 stroke

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    Stock jetting for your sled is 143.8 for the mains and 47.5 for the pilots.

    If you are at 145 mains and 47.5 pilots you are not lean with a stock engine and PSI quads. PSI actually recommended going down to 132 on the mains for an 800 with stage II mod quad pipes.

    If it was an actual lean burned piston it was from a dirty carb. If is was "blown" with physical damage not related to a typical burned piston it was more than likely from ingestion of one of the white air box tabs that are notorious for breaking off.

    opsled
    I reserve the right to change my mind if someone can prove to me it needs replacing.

  6. #6


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    Thanks for the info. Do you know where i can find more info on the pipes and compny?

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    Vmax4.com

    http://www.vmax4.com/content.php?

    Kind of slow this time of year.

    Here's a page on PSI from the Tech section.

    http://www.vmax4.com/blog.php?blogcategoryid=6

    opsled
    I reserve the right to change my mind if someone can prove to me it needs replacing.

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    a topic that was beat to death at vmax4.com . these are great pipes and add hp, but you needed to drop jetting for fast heat so they will make the power. in 1995 fuel was way better than the crap today. jet it atleast stock and be safe. parts for this motor are all but gone. 3:16x (yammie tony)
    WELCOME TO YAMAHA HEAVEN / WINTER THUNDER/ VMAX4 800 5.91 e.t.
    1995 VMAX 800- FASTEST YAMAHA EVER RUN AT THE AMERICAN SNOWMOBILER MAG SHOOTOUT. 105.16 mph
    2000 SRX 700 (10.458 @ 120.98, 1.39 60. on tar)
    2002 SRX 700 (110 in 1000 f.t. on radar 8bu-10)
    5.74 e.t. 85.15 on grass
    1979 srx 440
    YAMAHA PERFORMANCE SNOWMOBILES
    ''my old dinosaur just ate your new sled for lunch ''

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    They certainly are getting harder to find

  10. #10
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    i still grass drag a 1995 800 stocker. lots of parts on the shelf just in case. 3:16x (yammie tony)
    WELCOME TO YAMAHA HEAVEN / WINTER THUNDER/ VMAX4 800 5.91 e.t.
    1995 VMAX 800- FASTEST YAMAHA EVER RUN AT THE AMERICAN SNOWMOBILER MAG SHOOTOUT. 105.16 mph
    2000 SRX 700 (10.458 @ 120.98, 1.39 60. on tar)
    2002 SRX 700 (110 in 1000 f.t. on radar 8bu-10)
    5.74 e.t. 85.15 on grass
    1979 srx 440
    YAMAHA PERFORMANCE SNOWMOBILES
    ''my old dinosaur just ate your new sled for lunch ''

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